Preheat the oven to 175 degrees C.Grease a pan with butter of Section 24.
Beat the egg whites with a pinch of salt until stiff and then separate the egg yolks with the sugar, vanilla and lemon flavor to a creamy mass. Put the egg yolk in the frothy mixture. Add the cooled butter and fold in the flour, baking powder and a pinch of salt gradually through. Pour half of the batter into a 24 cm greased springform and place therein the peeled and sliced pears(which you mix with the juice of half a lemon) ,pour the rest of the batter over the pears and smooth out..sprinkle with powdered sugar. Bake on the rack in the middle of the oven for 60 minutes until golden.
Let cool for a few minutes and then remove the form from the cake .Eat warm with vanilla icecream.or just serve at room temperature with some sour cream.